This invention relates to automotive modular grills, primarily for trucks, and more specifically to roll-formed tubular members or bars with integral rolled locking systems which are used in the manufacture of the modular grills. Such tubular bars may be made from sheets of material of varying thickness taken from the group comprising stainless steel, high carbon steel, cold rolled steel and aluminum.
The automotive industry utilizes tubular bars in a wide variety of areas such as for bumpers, grills, frames and elsewhere throughout the vehicle where strength, cost, ease of manufacture and reduction in weight are desired. Such automotive products are subject to a variety of design requirements due to consumer demands, government regulations and the competitiveness of the industry. Tubular bars used in modular truck grills must maintain a high level of strength and damage resistance to meet consumer expectations and government regulations concerning low speed vehicle impact. However, such tubular members or bars must also be of low weight to assist in minimizing vehicular dead weight which reduces gas mileage. In addition, the tubular bars utilize, as an example, in truck grills must have a low manufacturing cost and be of high dimensional consistency given the competitiveness of the industry.
The present invention relates to an automotive tubular bar and the method of making such bar made of a material taken from the group comprising stainless steel, high carbon steel, cold rolled steel and aluminum roll-formed into a tubular cross section, with the bar having a controlled width and an integral rolled locking system which extends the entire length of the bar and hold the body of the bar in tension as the bar exits the roll mill.
The bar may be made from a variety of materials of varying thickness and rolled into a variety of cross sectional shapes, with the tubular bar usable in various automotive applications such as truck grills, door tracks and modular floor systems, to name a few.
In the past, it was necessary to squeeze the tubular bar after it exited the roll mill in order to hold the tubular bar together or, in other cases, mechanism fasteners were utilized or welding was required to maintain the bar in a closed tubular configuration. With the present invention, applicant utilizes the spring-back characteristics of the material to actually hold or maintain the tension of the tubular bar or part without resorting to mechanical fasteners, welding or squeezing of the part together. It is the metal itself that holds the bar or part together.
By forming a closed tubular section, the strength of the bar is greatly increased. This allows weight reduction by use of reduced material thickness. In addition, another important feature of the present invention is the formation of a sweep after the roll-forming process had been completed, with the rolled locking mechanism or system in place prior to the sweeping process occurring. This sweeping step allows for the manufacturer of tubular bars which satisfy modern automotive designs, increase the strength of the bar and improves it spring-back characteristics.
It is a feature of the present invention to provide a tubular member or bar comprising an elongated body formed to an established width on a roll forming machine and having an integral rolled locking mechanism, with the body having a pair of interconnected side walls with inner and outer surfaces, each side wall having a flange extending towards the other side wall and terminating in a lip along the longitudinal edge thereof, with each lip and flange extending the entire length of the body.
Another feature of the present invention is to provide a tubular bar of the aforementioned type with the flanges overlying one another, with the inner surface of one flange in surface-to-surface contact with the outer surface of the other flange, with the outer surface of one side wall having an elongated groove extending from one end of the body to the other end, with the groove receiving the elongated lip provided on the flange connected to the other side wall whereby the last mentioned lip and groove form the rolled locking mechanism which extends the entire length of the body and hold the body in intension.
Still another feature of the present invention is providing a tubular bar of the aforementioned type wherein the side walls of the body are of arcuate cross section and are connected by a generally U-shaped section extending lengthwise of the body.
A further feature of the present is to provide a tubular bar of the aforementioned type wherein the body has a sweeping curvature along the longitudinal length thereof for matching the bar with the contour of the surface upon which it is to be mounted.
A still further feature of the present invention is to provide a tubular bar of the aforementioned type wherein the overlying flanges are provided with alined openings for fasteners which permit the mounting of the tubular bar on a surface.
Another feature of the present invention is to provide a method of forming tubular bars comprising the steps of continuously providing an elongated strip of material of a predetermined width taken from the group comprising stainless steel, high carbon steel, cold rolled steel and aluminum and continuously moving the strip of material through roll forming assemblies which have shapes that as the sheet of material is passed therethrough, the material is gradually and progressively formed in succession into tubular bars with integral rolled locking mechanisms which extends the entire length of the bars and holds each tubular bar in tension as the bar exits the roll forming assemblies.
Another feature of the present invention is to provide a method of forming tubular bars including the step of subjecting the body to a sweep along its longitudinal axis to create a curvature consistent with the surface on which the tubular member is to be mounted.
Additional advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunctions with the accompanying drawings.